I've found Amazon Echo "skills" SDK far too complex for simple IoT / smart home devices, and the resulting UX is awkward and poor. Built-in echo support for wemo switches is better -- and can be emulated for arduino devices. +1
The Amazon Echo = game changer for my Arduino projects: a voice interface for wifi-enabled ESP8266 devices. Fits the command-based devices best.
I've been using a small board called the Oak from digistump for deploying arduino home-automation devices around the house. The Oak is a great board with good wifi, but the Particle firmware has always been trouble: difficult to set up, random flaky behavior, etc.
At heart the Oak is an ESP8266 chip, and these days there's a lot of independent support for ESP8266. So when I found some notes in the Oak forum about removing the Particle firmware and using the ESP8266 core directly, I jumped at the chance to try it out.